Conventional rotating machines used for instance as induction machines, synchronous machines or permanent magnet machines or the like comprise a rotor and a stator. The stator may be provided with a number of teeth each having an essentially similar shape both in its axial extension and in each radial cross section. The teeth are arranged on the inner periphery of the stator at equal distance from each other and are separated from each other by axially extending intermediate slots. In an inverted rotor machine the teeth are instead arranged on the outer periphery of the stator. The surface of each respective tooth facing the rotor in each radial cross section has the shape of a circular arc concentric to the envelope surface of the rotor. Furthermore, windings are arranged in the respective stator slots, and the air gap in a rotating electric machine may be constant both in its axial extension and in each radial cross section around the complete rotor. Permanent magnets are normally circumferentially disposed on the surface of the rotor and fixed to the surface of the rotor, for example, by means of a thin layer of adhesive.
Other known ways of mounting magnet elements on a rotor includes distinct preassembly of the magnet elements on a magnet holder, by means of an adhesive. Thereafter the magnet holder is attached to the rotor in a suitable way. Thus, the abovementioned methods use an adhesive as an essential component when mounting the magnet elements to the rotor, which implies that chemical compounds are needed in the production process of the rotor. Thus, production equipment suited for the handling of chemical compounds is needed, which implies a more expensive production. The adhesive is also a drawback upon recycling of the rotor, since special tools or chemical agents are needed in order to separate the different parts of the rotor from each other. It is also known to wrap a bandage of glass fibre/aramid fibre around the magnets in order to keep the magnets in place on the magnet holder, sometimes in combination with an adhesive, but this method is cumbersome and time consuming.
Thus, there is a need of an improved method for manufacturing rotors and, in particular to a method for mounting magnet elements on a rotor for use in permanent magnet motors.